Particulate detergents containing particles of an enzyme mixed with separate particles of a bleaching agent or a detergent builder are commonly used. It is known that the latter components may negatively affect the storage stability of the enzyme.
As a solution to this stability problem, the prior art suggests coating of the particles of the enzyme. It is known that the coating material needs to be carefully selected since it must on one hand protect the enzyme and on the other hand release the component rapidly when the detergent is dissolved.
As an example, WO 87/07292 (Novo) (which corresponds to U.S. Pat. No. 4,973,417) teaches that the use of an enteric coating on enzyme particles improves the stability in detergent with bleach; the enteric coating material dissolves at the pH of the detergent solution. However, we have found that this does not always give sufficient storage stability.
Thus, we have recognized that a need exists for a composition wherein the enzyme has improved stability during storage.